青海西秦岭双朋西矽卡岩型金-铜矿床流体包裹体研究  

Fluid inclusions study of Shuangpengxi skarn type gold-copper deposit in west Qinling, Qinghai Province

作　　者：路英川[1,2] 刘家军[1] 曹守林 张栋[2] 孙昊[2] 王斌[2] 张文华[2] 孔媛媛[2] 

机构地区：[1]中国地质大学地球科学与资源学院地质过程与矿产资源国家重点实验室,北京100083 [2]武警黄金地质研究所,河北廊坊065000 [3]青海省有色地质矿产勘查局七队,青海西宁810007

出　　处：《矿床地质》2016年第1期130-152,共23页Mineral Deposits

基　　金："中国地质调查局科外部科研项目(编号:1212011220899)";"中国地质调查局地质调查工作项目"(编号:1212011220924)";"国家自然科学重点基金项目(编号:41030423)"的联合资助

摘　　要：双朋西矽卡岩型金-铜矿床位于西秦岭造山带同仁-泽库弧后前陆盆地,为青海省秦岭西段代表性的矽卡岩型金-铜矿床。花岗闪长岩侵入以后,该矿床成矿期共有矽卡岩期（Ⅰ）和石英金属硫化物期（Ⅱ）两个期次,其中Ⅱ期又可以划分为早（Ⅱ-1）、晚（Ⅱ-2）两阶段。文章研究了3种包裹体类型：含子矿物水溶液包裹体（H型）、含CO2包裹体和盐水溶液包裹体。花岗闪长岩、矽卡岩期和石英硫化物期早阶段流体包裹体的均一温度和w（Na Cleq）分别为127-496℃,3.87%-21.11以及287-513℃,39.93%-58.41%;晚阶段为122-444℃,6.74%-46.80%;161-468℃,4.98%-35.06%,成矿流体属于中-高温、中-高盐度、中等密度、低-中压力的富CO2流体。S、Pb同位素显示成矿物质主要来自深源岩浆流体。H-O同位素组成显示主成矿期与岩浆水热液关系密切,随着成矿作用的演化,石英硫化物期晚阶段（Ⅱ-2）有大气降水混入。该矿床成矿作用与中酸性岩浆交代碳酸盐类围岩作用,流体的降温冷却和沸腾作用有关,区域局部伸展构造有助于成矿压力从静岩压力向静水压力转变,引起该地区成矿流体的减压沸腾作用,最终导致成矿物质沉淀富集。The Shuangpengxi skarn gold-copper deposit is located in the Tongren-Zeku back-arc foreland basin of Xiqinling orogenic belt. After the intrusion of the granodiorite, the metallogenetic epoch experienced sharn period（ Ⅰ）and the quartz sulfide period（ Ⅱ）,witch can be subdivided into the early stage（ Ⅱ-1） and late stage（ Ⅱ-2）. 3types of inclusions in the Shuangpengxi gold-copper deposit were studied in this paper： halitic fluid inclusion（ H）,carbon dioxide-bearing fluid inclusion, and liquid aqueous or two phase fluid inclusion. The homogenization temperatures of different rock types are 127 - 496℃, 287 - 513℃, 122 - 444℃ and 161 - 468℃, respectively, and the salinities range from 3. 87% to 21. 11%, 39. 93% to 58. 41%, 6. 74% to 46. 80% and 4. 98% to 35. 06%,respectively. The ore-forming fluids belonged to medium-high temperature, medium-high salinity, moderate density, and low-medium pressure salt solution with CO2. The S and Pb isotopic compositions show that ore-forming materials were mainly derived from deep source magmatic fluid. H-O isotopic composition indicates that the major mineralization fluid was associated with magmatic hydrothermalism, and during the evolution of the mineralization, theⅡ-2 stage fluids were mixed with meteoric water. The mineralization of the Shuangpengxi gold-copper deposit was connected with intermediate acid magmatic metasomatism of the carbonate rock, fluid cooling and fluid boiling. The decompression boiling, due to the pressure transformation from lithostatic to hydrostatic caused by regional partial local extension, eventually led to mineral precipitation enrichment.

关 键 词：地球化学 流体包裹体 双朋西金-铜矿床 西秦岭 

分 类 号：P618.41[天文地球—矿床学] P618.51[天文地球—地质学]